Describing Malvo as a teen-ager with average intelligence, David Schretlen testified that "he was unusually cheerful. It was almost a goofy affect that seemed quite out of step with the seriousness of the situation."

Malvo is facing the possibility of execution if he is convicted of either of two counts of murder in the fatal shooting Oct. 14, 2002, of FBI analyst Linda Franklin, which prosecutors contend was among 10 killings by snipers in the Washington area.

Defense attorneys have entered an insanity plea for Malvo, arguing that he was brainwashed by his accomplice in the shootings, John Allen Muhammad. Schretlen, who met with Malvo in August in the Fairfax County jail, was the first to testify in what will be several days of defense testimony by mental health witnesses.

The testimony followed that of witnesses who talked about Malvo's background and that of Muhammad, who jurors decided last month should be sentenced to death for the sniper attacks. The defense claims that Muhammad turned Malvo into a soldier in his private war against society.

Schretlen said that in a battery of tests and interviews, Malvo did not seem psychotic -- although in one test "he did describe himself as being socially alienated, detached from other people," Schretlen said.

With an IQ of 98, Malvo fell into the normal range. But Schretlen concluded that "Malvo produced an abnormal examination."

Schretlen said the results could have been affected by depression, a developmental delay, the anxiety clear from his sweaty palms or a "dissociative disorder" -- the brainwashing that the defense claims overwhelmed the youth's ability to tell right from wrong.

In a day of contentious objections, the Fairfax County prosecution team succeeded in blocking some testimony of defense witnesses. In getting the judge to agree with them about the manner in which the defense's cult expert could be quizzed, prosecutors so flustered the defense that it pulled the expert off the stand so it could rework its line of questioning overnight.

"One of the problems with this case is that we have an insanity defense that is like a puff of smoke," Fairfax County Commonwealth's Attorney Robert F. Horan Jr. argued.

The defense attorneys are relying heavily on mental health experts. More than half a dozen of them are being called to meld about five days of sometimes disjointed testimony by other witnesses into a cohesive picture of an adolescent who they contend was molded into a racist America-hating killer over nearly two years by a soured adult who blamed "the system" and whites for his failures.

Muhammad was portrayed by the defense as a control freak, who a decade ago tried to brainwash his 11-year-old son from his first failed marriage.

The 42-year-old Muhammad's military experience, described in government records and testimony by his sergeant, Kip Berentson, is pocked with problems. Muhammad complained that Berentson, who is white, picked on him because he is black, and contended he was falsely accused in a "fragging" incident in which an incendiary grenade was thrown into Berentson's tent.

Malvo's attorneys contend that Muhammad trained Malvo, who at 15 was given by his mother to Muhammad as collateral for fake travel papers, into his way of thinking and made him a polished sniper.

Part of Muhammad's plan was to take 70 boys and 70 girls to start a new and "just" society in Canada, buying land and equipment for a compound with the $10 million the snipers hoped to extort from the government to end the Washington-area sniper siege.

Carmeta Albarus, a court-appointed social worker from Jamaica who spent several days interviewing Malvo, said the teen-ager she met in March had lost his Jamaican accent and insisted that he was Muhammad's son and that authorities were using him to kill his "father." She said he spewed an "oratory of racial injustice."

She attempted to pull him toward his Jamaican roots, developing a rapport with him over 70 hours, she testified. Albarus said the 18-year-old "reverted to his Jamaican accent" and Patois dialect as he listened to an audiotape of his father's reminiscences of him in Jamaica.

In a telephone conference with his father, Malvo started out calling him "sir" -- a formality that Muhammad taught him to adhere to while addressing men. "As the conversation progressed, he reverted to Dada," Albarus said.